1. Field of the Invention
The present invention relates to a communication system which is arranged by connecting a plurality of communication devices through a data transmission line and exchanges data between the communication devices, more specifically, relates to a communication method and communication system in which when communication data are transmitted from an arbitrary originating source communication device to the other plural destination communication devices and the originating source communication device receives responses including receiving states of the respective destination communication devices, the originating source communication device can receive all the responses from the respective destination communication devices securely without conflict of the responses.
2. Description of the Related Art
There is known a communication system which is arranged by connecting a plurality of communication devices through a data transmission line and exchanges data between the communication devices.
The above conventional communication system is occasionally required to multiply transmit communication data suitably including various commands and control information from an arbitrary communication device to the other plural communication devices. In this case, for example, inherent multiple addresses such as "FF" are preset as for plural destination communication devices which are prescribed multiple destinations of the communication data to be transmitted in this time. The arbitrary communication device which is a transmission source adds the multiple addresses "FF" as destinations of the communication data to be transmitted in this time, and transmits the communication data to which the multiple addresses were added to the destination communication devices whose multiple addresses "FF" are set. Then, the respective destination communication devices judge as to whether or not the multiple addresses "FF" added to the communication data coincide with the self multiple addresses, and when as a result of the judgment, the multiple addresses "FF" coincide with the self multiple addresses, namely, when the respective destination communication devices are specified as the multiple addresses, a process for capturing the communication data into the respective destination communication devices is performed. Furthermore, the responses including receiving states of the respective destination communication devices are transmitted back to the originating source communication device so that when the capturing of the communication data is succeeded, acknowledgment (ACK) is transmitted back, whereas when the capturing of the communication data is failed, negative acknowledgment (NAK) is transmitted back.
However, according to the aforementioned communication method in the conventional communication system, when one originating source communication device receives responses including receiving states of plural destination communication devices, if the respective responses are overlapped at the same time, it is difficult that the originating source communication device receives all the responses from the destination communication devices securely due to conflict of the responses. Namely, this method has such a problem which should be solved.